Heavy rainfall from thunderstorms could cause localized flooding in northeastern Indiana, southern Lower Michigan and northwestern Ohio today, according to the “Hazardous Weather Outlook” that the northern Indiana office of the National Weather Service (NWS) issued at 5:43 a.m. Some strong storms this afternoon and early evening could produce wind gusts to 45 mph. While some storms might be strong, forecasters do not expect any of them to reach severe thunderstorm criteria (winds of at least 58 mph and/or hail of at least one inch in diameter).

There’s a chance of thunderstorms in northeastern Indiana through Friday and again Sunday afternoon through Tuesday, but forecasters do not expect severe storms, according to the “Hazardous Weather Outlook” the northern Indiana National Weather Service (NWS) office issued at 5:23 a.m. EDT.

Nonetheless, an isolated strong wind gust or small hail might be possible today or tonight. And Friday’s storms could produce very heavy rainfall and localized flooding.

URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 321
   NWS STORM PREDICTION CENTER NORMAN OK
   155 PM EDT WED JUN 18 2014

   THE NWS STORM PREDICTION CENTER HAS ISSUED A

   * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
     NORTHERN INDIANA
     CENTRAL AND SOUTHERN LOWER MICHIGAN
     NORTHWEST OHIO
     LAKE ERIE

   * EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 155 PM
     UNTIL 900 PM EDT.

   * PRIMARY THREATS INCLUDE...
     SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
     ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE

   THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
   STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES NORTHEAST OF
   FLINT MICHIGAN TO 70 MILES WEST SOUTHWEST OF TOLEDO OHIO.  FOR A
   COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
   UPDATE (WOUS64 KWNS WOU1).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
   FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
   DO PRODUCE TORNADOES.

   &&

   DISCUSSION...A QLCS WITH EMBEDDED BOWING STRUCTURES SHOULD CONTINUE
   TO INTENSIFY AS IT MOVES EAST AND SOUTHEAST ACROSS THE WATCH AREA
   THIS AFTERNOON. DAMAGING WINDS WILL BE THE PRIMARY HAZARD...THOUGH
   ISOLATED OCCURRENCES OF LARGE HAIL ARE ALSO POSSIBLE.

   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
   MOTION VECTOR 27035.

BULLETIN - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH OUTLINE UPDATE FOR WS 321
   NWS STORM PREDICTION CENTER NORMAN OK
   155 PM EDT WED JUN 18 2014

   SEVERE THUNDERSTORM WATCH 321 IS IN EFFECT UNTIL 900 PM EDT
   FOR THE FOLLOWING LOCATIONS

   INC001-003-033-039-049-069-085-087-099-103-113-131-141-151-169-
   179-183-190100-
   /O.NEW.KWNS.SV.A.0321.140618T1755Z-140619T0100Z/

   IN 
   .    INDIANA COUNTIES INCLUDED ARE

   ADAMS                ALLEN               DE KALB             
   ELKHART              FULTON              HUNTINGTON          
   KOSCIUSKO            LAGRANGE            MARSHALL            
   MIAMI                NOBLE               PULASKI             
   ST. JOSEPH           STEUBEN             WABASH              
   WELLS                WHITLEY             


   MIC015-023-025-027-037-045-049-059-065-075-077-087-091-093-099-
   115-125-147-149-155-161-163-190100-
   /O.NEW.KWNS.SV.A.0321.140618T1755Z-140619T0100Z/

   MI 
   .    MICHIGAN COUNTIES INCLUDED ARE

   BARRY                BRANCH              CALHOUN             
   CASS                 CLINTON             EATON               
   GENESEE              HILLSDALE           INGHAM              
   JACKSON              KALAMAZOO           LAPEER              
   LENAWEE              LIVINGSTON          MACOMB              
   MONROE               OAKLAND             SHIAWASSEE          
   ST. CLAIR            ST. JOSEPH          WASHTENAW           
   WAYNE                


   OHC003-039-051-063-069-095-125-137-161-171-173-190100-
   /O.NEW.KWNS.SV.A.0321.140618T1755Z-140619T0100Z/

   OH 
   .    OHIO COUNTIES INCLUDED ARE

   ALLEN                DEFIANCE            FULTON              
   HANCOCK              HENRY               LUCAS               
   PAULDING             PUTNAM              VAN WERT            
   WILLIAMS             WOOD       

 The National Weather Service Storm Prediction Center has issued Mesoscale Discussion #1061, which indicates a 40 percent chance of a watch being issued that could include northern Indiana.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1013 AM EDT WED JUN 18 2014 /913 AM CDT WED JUN 18 2014/

...NOAA WEATHER RADIO TEST POSTPONED...

TODAYS NOAA WEATHER RADIO WEEKLY TEST WILL BE POSTPONED DUE TO THE
THREAT FOR SEVERE WEATHER THIS AFTERNOON. WE WILL RESCHEDULE THE
TEST FOR THURSDAY JUNE 19 BETWEEN 11 AM AND NOON.

Probability of damaging thunderstorm winds or wind gusts of 50 knots (58 mph) or higher within 25 miles of a point. Red area: 30%. Yellow area: 15%. Remaining area: Less than 15%. Highlighted counties: Northern Indiana NWS office county warning area. Source: SPC “Day 1 Convective Outlook,” 8:54 a.m. EDT. Read about probability figures.

The probability of damaging straight-line winds in northeastern Indiana, southern Lower Michigan and northwestern Ohio today and tonight has increased, according to an updated “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 8:54 a.m. EDT.

For the entire 37-county warning area of the northern Indiana NWS office, the outlook increases from 15 percent to 30 percent the probability of damaging thunderstorm winds or wind gusts of 50 knots (58 mph) or higher within 25 miles of a point. A probability of 30 percent is on the high end of the “slight risk” category. You can get some detailed information what the probability figures mean on the SPC website, but here’s a brief explanation: If you consider that on a typical June 18, the probability of damaging thunderstorm winds occurring within 25 miles of you is probably one percent or less, the probability today is at least 30 times higher than on a typical day.

Don’t underestimate the damage potential of 58 mph straight-line winds! According to the Beaufort Wind Scale, winds of 48 mph to 55 mph can uproot trees and cause considerable structural damage. So even though the risk of tornadoes today is low, it’s a good day to pay attention to weather watches and warnings.

See an important update to this story: Latest outlook increases wind risk

The northern three fourths of Indiana, as well as large areas of other states, have a slight risk of severe weather between 8 a.m. EDT today and 8 a.m. EDT tomorrow, according to the “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 2:10 a.m.

The slight risk area includes the entire 37-county warning area of the northern Indiana NWS office.

In Indiana, Michigan and Ohio, the primary threats are damaging straight-line winds of 50 knots (58 mph) or more and hail of one inch in diameter or larger. The probability of either happening within 25 miles of a point is 15 percent. The probability of a tornado within 25 miles of a point in Indiana, Michigan and Ohio is two percent. Read more about outlook probabilities.

The numbers are a little higher to the west. Parts of Illinois, Wisconsin, Iowa, Minnesota and the Dakotas — while still in a slight-risk area — have a 30 percent probability of damaging thunderstorm winds and large hail and a five percent probability of a tornado.

SKYWARN storm spotter activation might be needed this afternoon or tonight, according to the “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 4:52 a.m.

Anyone in the slight risk area should have a way to be informed of any watches or warnings that the NWS issues today, especially if they are involved in outdoor activities.

The SPC will update its convective outlooks for today by 9 a.m. and again at 12:30 p.m., 4 p.m. and 9 p.m. EDT.